Projector and method for controlling image display of the same

Abstract

A projector in which an additional writing image is synthesized with a projection image and the synthesized image is projected and displayed includes: a display memory storing trapezoidal distortion corrected projection image information; a pen drawing control part forming an additional writing image by straight line drawing based on display position information of an inputted additional writing image and corrects trapezoidal distortion; and an OSD memory storing additional writing image information generated in the pen drawing control part and having corrected trapezoidal distortion, in which image information in the display memory and image information in the OSD memory are synthesized and displayed. Recording of projection image information into an external storage device includes setting an output image to BLANK; storing a projection image without correcting trapezoidal distortion into the display memory; and synthesizing the contents of the display memory and the additional writing image to into the external storage device.

What is claimed is: 
     
         1 . A projector in which an additional writing image is synthesized with a projection image and the synthesized image is projected and displayed, the projector comprising:
 a display memory which stores trapezoidal distortion corrected projection image information;   a pen drawing control part which forms an additional writing image by straight line drawing based on display position information of an inputted additional writing image and corrects trapezoidal distortion; and   an OSD memory which stores additional writing image information being generated in the pen drawing control part and in which trapezoidal distortion is corrected,   wherein image information in the display memory and image information the OSD memory are synthesized and displayed.   
     
     
         2 . A method for controlling image display of a projector in which an additional writing image is synthesized with a projection image and the synthesized image is projected and displayed, the method comprising:
 inputting pieces of coordinate information of an additional writing image which is synthesized with a projection image and displayed;   drawing a straight line of which the pieces of coordinate information are used as edge parts;   transforming a coordinate of projection image information in accordance with a correction amount of trapezoidal distortion;   transforming a coordinate of the additional writing image in which the straight line is drawn in accordance with a correction amount of trapezoidal distortion;   synthesizing the coordinate transformed projection image information with the coordinate transformed additional writing image information; and   magnifying and projecting the synthesized projection image information.   
     
     
         3 . The method for controlling the display of the projector according to  claim 2 , further comprising:
 setting an output image of a projection image BLANK;   storing projection image information into a display memory without coordinate transformation in accordance with a correction amount of trapezoidal distortion;   setting the display memory a FREEZE status;   synthesizing image data in the display memory with the additional writing image formed by the step of drawing the straight line of which the pieces of coordinate information are used as the edge parts;   writing the image information synthesized in the previous step into an external storage means;   resuming the step of transforming the coordinate of the projection image information in accordance with the correction amount of the trapezoidal distortion;   canceling the FREEZE status of the display memory; and   canceling the BLANK status of the output image of the projection image,   wherein the projection image synthesized with the additional writing image is written into the external storage means.   
     
     
         4 . A method for controlling an image display of a projector in which an additional writing image is synthesized with a projection image and the synthesized image is projected and displayed, the method comprising:
 inputting pieces of coordinate information of an additional writing image which is synthesized with a projection image and displayed;   transforming pieces of coordinate information of the additional writing image to a plurality of corrected trapezoidal coordinates with reference to a coordinate transformation table;   drawing a straight line of which the pieces of corrected trapezoidal coordinate information are used as the edge parts to create an additional writing image;   transforming a coordinate of projection image information in accordance with a correction amount of trapezoidal distortion;   synthesizing the coordinate transformed projection image information with the coordinate transformed additional writing image information; and   magnifying and projecting the synthesized projection image information.   
     
     
         5 . The method for controlling display the projector according to  claim 4 , further comprising:
 setting an output image of a projection image BLANK;   storing projection image information into a display memory without coordinate transformation in accordance with a correction amount of trapezoidal distortion;   setting the display memory a FREEZE status;   synthesizing image data in the display memory with an additional writing image created by reverse trapezoidal correction transformation of the additional writing image created in the step of drawing the straight line of which the pieces of corrected trapezoidal coordinate information are used as the edge parts to create an additional writing image;   writing the image information synthesized in the previous step into an external storage means;   resuming the step of transforming the coordinate of the projection image information in accordance with the correction amount of the trapezoidal distortion;   canceling the FREEZE status of the display memory; and   canceling the BLANK status of the output image of the projection image,   wherein the projection image synthesized with the additional writing image is written into the external storage means.